Bioavailability of Potassium From Three Dosage Forms: Suspension, Capsule, and Solution

Abstract

A crossover study was performed in 28, healthy, male volunteers to determine the bioavailability of potassium from a suspension containing microencapsulated potassium chloride compared with that from a marketed microencapsulated potassium chloride capsule and a marketed potassium chloride solution. The 20-day study consisted of four, five-day periods. In three of the periods, a single, 40-mEq dose of one of the potassium formulations was administered; no drug treatment was given in the remaining period so that the amount of potassium contributed by dietary sources could be determined. Meals were served that provided controlled amounts of potassium and sodium. Bioavailability was represented by cumulative amount of K+ excreted in urine 24 and 48 hours after drug administration. The rate of absorption was calculated from excretion rates during each of the intervals of urine collection on Days 4. The pattern of excretion exhibited by the solution indicated rapid absorption and elimination. The potassium from the suspension and the capsules was excreted more slowly and over a longer period, indicating that the potassium content from these formulations was not being dumped. No statistically significant differences between the suspension and the capsules were found. The extent of absorption of K+ was similar from all three products, and the potassium from the suspension was found to be fully bioavailable when compared with the liquid and the capsule.

The Pharmacokinetics of Potassium in Humans Is Unusual

“…On the treatment day a single peak excretion rate can be observed 1 hour after administration. Following the absorption phase, the decline of the profile of K + exo,dose is characterized by 2 disposition phases with apparent half‐lives of 1.6 and 14 hours when using the data by Melikian et al or 2.5 and 13 hours when using the data by Caplain et al . Similar disposition phase half‐lives for K + exo,dose after administration of a KCl solution were reported by Rakhit et al…”

“…Homeostasis of K + endo is evidenced by small variations (CV = 4.3%) in the daily urinary recoveries of ࢣ(K + endo + K + exo,diet ) on 5 control days. 17 Of note, the contribution of K + endo to ࢣ(K + endo + K + exo,diet + K + exo,dose ) in plasma is large and much greater than in urine. The amounts of K + endo recovered in urine are minimal.…”

Potassium Intake, Bioavailability, Hypertension, and Glucose Control

“…The small intestine is the primary site of potassium absorption, with approximately 90% of dietary potassium being absorbed by passive diffusion [ 29 ]. Little is known about the bioavailability of potassium, with the majority of work being centered on the assessment of urinary potassium losses after potassium salt supplementation [ 30 , 31 , 32 ].…”

New Guidelines for Potassium Replacement in Clinical Practice

“…It is clear that controlled clinical studies are necessary to determine the specific recommendations. Fewer erosions than wax-matrix tablets [38][39][40][41][42] Potassium chloride elixir Inexpensive, tastes bad, poor compliance; few erosions; immediate effect 43,44 Potassium chloride (effervescent tablets) for solution…”